1. Technical Field
The present invention relates generally to an improved overlash jig. More particularly, the invention relates to a device for pulling a cable along a support line of the type supported between utility poles. Specifically, the invention relates to a device for pulling a cable along a support line which retains tension on the cable even as the cable is maneuvered around a utility pole.
2. Background Information
Utility poles often support high-voltage power lines, cables for transmitting cable television, and telephone lines. Generally, utility poles are owned by a single power company, and the power company charges other utility companies an annual fee for stringing cables on poles which it owns. For example, a given utility company may pay the power company an annual fee for each pole connection necessary to support its cables.
When new cables are installed on utility poles, they must be of sufficient strength and rigidity to withstand wind and weather, as well as to support the weight of the cable as it is suspended from the utility poles.
As both rural and urban areas continue to expand, the need to string additional cables on existing utility poles also continues to grow. This is especially true given the increased popularity of cable television. To avoid pole connection expenses, it is becoming increasingly common to lash new cables to cables already positioned on and connected to utility poles. Special tools are available that travel along the existing line and play out a lashing wire that spirals around the new cable to lash it to an existing line.
The lashing of new cables onto existing lines also permits a less rigid, and consequently less expensive, cable to be utilized. Specifically, the existing line is closely lashed to the new cable, and as such, the new cable is not required to support its own weight as the existing line will carry a portion of that load. As such, the lashing of new cables onto existing cables is significantly less expensive than the alternative of stringing independent cables on utility poles.
Heretofore, a number of overlash jigs have been developed which are presumably sufficient for the purpose for which they are intended. In operation, a cable that is to be pulled along an existing support line is first attached to the overlash jig. The overlash jig is then supported via a plurality of rollers on the support cable. The jig is then towed via a tow vehicle so that the jig rolls along the support line pulling the new cable at the same speed the vehicle is moving.
When the overlash jig encounters an obstacle such as a tree, mid-span drop, or more commonly, a utility pole, the vehicle is stopped and the tow rope disconnected from the jig. An effort has been made to hold the new cable in position on the support line, while the obstacle is circumvented. The free end of the tow rope is then brought around, or under, the obstacle as conditions require, and is reconnected to the jig so that the vehicle can resume its forward travel, again towing the jig and hence pulling the new cable. When the reconnection has been made, the means holding the new cable in position is released.
One of the drawbacks of the above-described process is the lack of any suitable device or system for holding the new cable in position while the tow rope is released from the overlash jig. If the new cable has been pulled a very short distance when the obstacle is encountered, one person can retain the cable in position. However, if the cable has already been pulled a significant distance, then the force exerted on the cable will be significant, and the user must find another means of holding the cable in position as the overlash jig is moved around the obstacle.
A variety of clamps have been developed which are presumably adequate for the purpose for which they are intended. These clamps attempt to clamp the cable to the support line to prevent the cable from retreating therealong. If the cable does retreat along the support line, it will slack and sag, possibly blocking driveways, roads and parking lots.
One problem inherent with prior retaining clamps is that the use thereof is labor intensive as the clamps are time consuming to apply and remove. Further, if a cable has been pulled a significant distance, the cable weight may be sufficient to cause the clamp to slip, and the cable will slacken unless the clamp is further tightened. Such further tightening, while sufficient to hold the cable in position, may damage one or both of the cable or support line.
U.S. Pat. No. 5,040,771 attempted to overcome a number of the problems associated with the above-discussed clamps by including a brake mechanism in the overlash jig. While the overlash jig of the '771 patent is presumably adequate for the purpose for which it was intended, it still does not provide an effective braking mechanism, and may inadvertently be pulled from the support line when in use. Moreover, once the tow rope of the '771 patent is relaxed and the brake system applied to the support line, the brake system cannot be manually disengaged to remove the overlash jig from the support line, substantially reducing the effectiveness of the unit.
Thus, the need exists for an overlash jig which is retained on the support line and which secures the support line within the overlash jig. Moreover, the need exists for an overlash jig which provides an effective braking and guiding mechanism, and wherein the braking mechanism may be manually disengaged without the need for reapplying tension to the tow line attached thereto.